This invention relates to woodworking planes, particularly including bench planes having cast metal bodies.
One of the more fundamental operations in working wood is controlled removal of wood tissue in order to leave a planar surface. Planes are the most commonly used tools for accomplishing this, and enormous effort has therefore been expended in the development and refinement of planes. All planes include at least two elements: a plane body or blade holder of some sort and a blade that is fixed (often adjustably) to or in the plane body or holder so that wood tissue is cut when the blade and body assembly are moved relative to a work piece. Usually at least one surface of the plane body or holder is in contact with the workpiece. The earliest plane bodies were typically wood. In the 19th century, planes were developed with metal parts in addition to the blade but wood soles for workpiece contact, and subsequently planes were developed having cast metal bodies, including the sole.
One of the larger and more important classes of planes are known as xe2x80x9cbench planes,xe2x80x9d and the general configurations and sizes of bench planes in western woodworking have become standard and are commonly designated with numerals including numbers 3, 4, 4{fraction (1/2,)} 5, 6 and 7.
A successful bench plane must provide several specific functions and features. It must provide a mechanism for positioning a plane blade to protrude through an opening (the xe2x80x9cmouthxe2x80x9d) in a planar registration surface, called the xe2x80x9csole,xe2x80x9d for contact with the workpiece. It is desirable that the distance between the position of the blade within the mouth and the leading edge of the mouth be small but adjustable, that the projection of the blade through the mouth be adjustable, and that the lateral tilt of the blade within the plane in which it is positioned be adjustable. It is desirable that the blade be held within the plane in a very secure manner and that it be supported in a way that minimizes bending or flexing of the blade in response to the forces exerted on it during use of the plane.
The manner in which a plane blade is held within the plane structure and extent to which it is supported, particularly adjacent to the blade cutting edge or arris is important to the successful function of the plane. A narrow mouth reduces tear-out during use of the plane but limits chip clearance and thereby limits the possible thickness of shavings that can be taken. Adjustability of blade position relative to the mouth can be achieved by securing the plane blade to an appropriately sloping surface of the frog (the xe2x80x9cbedxe2x80x9d) and adjustably securing the frog to the plane body so that sliding the frog back and forth moves the plane blade back and forth within the mouth. Such adjustable-position frogs are well known in the art. However, conventional adjustable-frog plane designs generally suffer from at least three problems. First, the frog position frequently is not adjustable without removing the plane blade, which tends to dissuade users from adjusting frog position, and the frog often is not secured to the plane body with sufficient rigidity. Second, once the blade is removed to gain access to the frog securing screws, when the screws are loosened not only can the frog move fore and aft, but is also free to move laterally and to pivot slightly because the screws pass through slotted holes in the frog. While this is advantageous in that tight dimensional tolerances are not required on account of the adjustability available, it also makes proper adjustment or resetting the frog a time consuming and difficult effort. Third, and most important, because the frog (and therefore the bed) lies entirely above the portion of the plane body on which it rests, but the blade must project down below the surface or sole of the plane body, a portion of the blade projecting below the frog is unsupported.
Another limitation associated with conventional bench planes is the fixed bed angle. Bench plane blades are used with the arris-forming bevel down, so the bed angle of the frog, i.e., the angle between the frog surface against which the plane blades lies and the sole of the plane, determines the cutting angle of the blade. The bed angle of bench plane frogs is fixed, and therefore cannot be changed to alter the plane blade cutting angle, but different cutting angles can be desirable under differing planing circumstances.
Different woodworking operations require the use of different sizes of planes, so it is not possible to produce a single bench plane that functions optimally in all situations. However, the principal difference among bench planes is the length of the sole, and it is therefore possible to manufacture a line of bench planes using a substantial number of parts that are interchangeable among plane sizes. Such interchangeability provides two potential benefits. The first is reduction in manufacturing complexity resulting from reduction in the number of parts that need be manufactured for an entire bench plane line. Second is the possibility of reusing certain of the same parts with different plane soles in order to provide bench planes of different sizes. The practical utility of using parts with different soles, however, is determined to some extent by the ease with which such parts can be moved from one sole to another.
Despite the long history of bench plane development, these considerations leave room for further improvement of such planes.
This invention improves prior bench plane designs and makes practical interchangeability of components among plane bodies of different sizes, which facilitates manufacture of a wide range of plane sizes differing in both width and length utilizing an economically small number of components. In the bench planes of this invention, the rear plane handle or tote is captured between and secured soley to projecting tines attached to a frog that is adjustably secured to a plane body in a manner permitting forward and backward adjustment of the frog position without removing the plane blade. Plane blade lateral and depth adjustment is accomplished utilizing a mechanism also secured entirely to the frog, thereby providing a frog, blade and handle assembly usable interchangeably on plane bodies of differing lengths. The design of the frog and lever cap permit utilization of the same frog and lever cap castings for bench planes and blades of differing widths, because the component widths can be easily reduced by machining and/or grinding relatively small amounts of materials off of each side of the components.
Of critical importance, the frog of the invention extends through the plane body to provide a xe2x80x9cfootxe2x80x9d having a bottom surface co-planar with the sole that contacts the workpiece together with the sole. This extension provides contact with the underside of the plane blade all the way down to the blade bevel, thus providing the maximum such blade contact possible. This provides support nearer the blade cutting edge or arris than conventional metal component plane frogs provide and thereby reduces blade chatter.
Superior lateral blade position control is provided by set screws having flat ends penetrating the two sides of the plane body immediately above the mouth. These set screws prevent lateral movement of the plane blade adjacent to the arris, thus improving function of the lateral adjustment mechanism and reducing the likelihood of lateral blade position shifts during use of the plane.
The frog/blade/handle assembly of this invention is usable with multiple lengths of plane bodies and can be easily modified for use with multiple widths of plane bodies. Set screws or other structures in one of the frog or plane body for contact wit the other of the plane body and frog permit adjustment accommodating differences in plane body thicknesses.
Adjustments in the blade cutting angle without modifying the angle at which the blade is held by the frog in the plane may be made by forming a front bevel on the front surface of the blade (xe2x80x9cfrontxe2x80x9d meaning the side of the blade facing forward and up when it is in the plane).